SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c52de17242034f1866db437a478b92ff160242feeae0c8c9fb0ac8997003b571' 
  AND token = 'BsydmmyNHm3ERnCOh/p8P5B3c0F8hgXsHjkFQUvzItU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}